imageline()

(PHP 4, PHP 5, PHP 7)

画一条线段

说明

imageline() 用$color颜色在图像$image中从坐标$x1，$y1到$x2，$y2（图像左上角为 0, 0）画一条线段。

画一条粗线

参见 imagecreatetruecolor() 和 imagecolorallocate()。

This is a function to make a dotted line. It accepts (it actually requires) 7 parameters and returns 1 if everything went OK and 0 if there was a problem.
int imagelinedotted ( resource im, int x1, int y1, int x2, int y2, int dist, int col )
imagelinedotted() draws a line from x1, y1 to x2, y2 (top left is 0, 0) in image im of colour col where dist defines the distance (measured in pixels) between one dot and another. 

I've modified the previous entry for drawing on a polar coordinate system to better represent angles based on a 360º whole circle bearing. 

Here my function do clear all problems. With this, you can draw firstly smooth lines (basic code adapted from code_couturier at graffiti dot net, with some performance changes). The special is, you can define the alpha-value of the line (0 = normal smooth line, 127 = fully transparent). Change whatever you want to make it better, but post your results ;) 

Here is a simple code to draw a line with an arbitrary stroke. The parameter aStroke is treated as a cyclic boolean array where true equals "set a point"
e.g. $aDotStroke = array(true,false);
function ImageStrokeLine($im,$x1,$y1,$x2,$y2,$farbe, $aStroke)
 {
  $deltax = abs($x2 - $x1);    
  $deltay = abs($y2 - $y1);    
  $x = $x1;            
  $y = $y1;            
  
  if ($x2 >= $x1)         
  {
   $xinc1 = 1;
   $xinc2 = 1;
  }
  else             
  {
   $xinc1 = -1;
   $xinc2 = -1;
  }
  
  if ($y2 >= $y1)         
  {
   $yinc1 = 1;
   $yinc2 = 1;
  }
  else             
  {
   $yinc1 = -1;
   $yinc2 = -1;
  }
  
  if ($deltax >= $deltay) 
  {
   $xinc1 = 0;         
   $yinc2 = 0;         
   $den = $deltax;
   $num = $deltax / 2;
   $numadd = $deltay;
   $numpixels = $deltax; 
  }
  else             
  {
   $xinc2 = 0;       
   $yinc1 = 0;       
   $den = $deltay;
   $num = $deltay / 2;
   $numadd = $deltax;
   $numpixels = $deltay; 
  }
  
  for ($curpixel = 0; $curpixel = count($aStroke))
   {
    $iStrokeCount = 0;
   }
 
   if ($aStroke[$iStrokeCount++]) 
   {
    ImageSetPixel($im,$x, $y,$farbe);      
   }      
   $num += $numadd;      
   if ($num >= $den)       
   {
    $num -= $den;        
    $x += $xinc1;        
    $y += $yinc1;        
   }
   $x += $xinc2;         
   $y += $yinc2;         
  }
 }

A quick function using imageline that I wrote so i could specify a starting point, angle and length of vector.
Thought other people might find this useful.

For this script angles work in a anti-clockwise direction (modify + and - in function to change start of 0 degrees and also direction of angle calculated)

Here is a analog clock representation of the system time along with digits for hours and little dots for minutes/seconds: 

Here is a function for making antialiased lines:
 function imagesmoothline ( $image , $x1 , $y1 , $x2 , $y2 , $color )
 {
 $colors = imagecolorsforindex ( $image , $color );
 if ( $x1 == $x2 )
 {
  imageline ( $image , $x1 , $y1 , $x2 , $y2 , $color ); // Vertical line
 }
 else
 {
  $m = ( $y2 - $y1 ) / ( $x2 - $x1 );
  $b = $y1 - $m * $x1;
  if ( abs ( $m ) 

// Here's a function for drawing a rotated gradient Rectangle (based on a previous note)
// Create An Image 255x255
$img = ImageCreateTrueColor(255, 255);
GradientRect($img,50,50,80,80,30);
ImagePng($img,"test.png");
ImageDestroy($img);
echo "
";
function GradientRect($img, $x1, $y1, $x2, $y2, $wdt) {
 $alpha = atan2($y2-$y1,$x2-$x1);
 $real_wdt = $wdt*sin($alpha);
 $real_hgt = $wdt*cos($alpha);
 echo "real wdt:".$real_wdt;
 echo "
real hgt:".$real_hgt;
 echo "
angle: ".($angle*180/pi());
 $plotD = 0;
 $i=0; 
 $dy = $real_hgt/$wdt;
 $dx = $real_wdt/$wdt;
 $drgb= 256/$wdt;
 while($i++ 
Simple function to create border for jpg-images:
function createImageBorder($imgName){
   $img   = substr($imgName, 0, -4); // remove fileExtension
   $ext   = ".jpg";
   $quality = 95;
   $borderColor = 255; // 255 = white
   
  /*
   a             b
   +-------------------------+
   |             
   |     IMAGE      
   |             
   +-------------------------+
   c             d  
  */
  
  $scr_img = imagecreatefromjpeg($img.$ext);
  $width  = imagesx($scr_img);
  $height = imagesy($scr_img);
       
    // line a - b
    $abX = 0;
    $abY = 0;
    $abX1 = $width;
    $abY1 = 0;
    
    // line a - c
    $acX = 0;
    $acY = 0;
    $acX1 = 0;
    $acY1 = $height;
    
    // line b - d
    $bdX = $width-1;
    $bdY = 0;
    $bdX1 = $width-1;
    $bdY1 = $height;
    
    // line c - d
    $cdX = 0;
    $cdY = $height-1;
    $cdX1 = $width;
    $cdY1 = $height-1;
      
    // DRAW LINES  
    imageline($scr_img,$abX,$abY,$abX1,$abY1,$borderColor);
    imageline($scr_img,$acX,$acY,$acX1,$acY1,$borderColor);
    imageline($scr_img,$bdX,$bdY,$bdX1,$bdY1,$borderColor);
    imageline($scr_img,$cdX,$cdY,$cdX1,$cdY1,$borderColor);
    
   // create copy from image  
    imagejpeg($scr_img, $img."_border.jpg", $quality);
    imagedestroy($scr_img); 
 }
  
  createImageBorder("myfile.jpg");
an algorithm to draw a bezier spline 
This function draw border to image.
function imageborder($img,$color) {
  $width = imagesx($img);
  $height = imagesy($img);
  ImageLine($img, 0, 0, $width, 0, $color);
  ImageLine($img, 0, 0, 0, $height, $color);
  ImageLine($img, $width-1, 0, $height-1, $height, $color);
  ImageLine($img, 0, $height-1, $width, $height-1, $color);
}
If you draw on a canvas, using js ctx.lineJoin = "round"; and then try to do the same on a GD $img the result will not be the same. 
Here is a simple code to draw a line similar to one made using lineJoin round.
$w=5; //set your line thickness;
imagesetthickness($img, $w);
imageline($img, $x1, $y1, $x2, $y2, $color);
imagesetthickness($img, 1);
imagefilledellipse ( $img , $x2 , $y2 , $w ,$w, $color);
The most bold-line-functions i found have problems with lines in a certian direction (they draw smaller lines with some angles). To do a real bold line just use this function: 
An example to draw Amplitude Modulation curve: y = c * sin (x/a) * sin (x/b) . You can easily modify the codes to create your own oscilloscope application!

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